second, click to view older messages, this will put a new timestamp in your url, which we will touch on more in the next step.
look for the first timestamp in your url, this is essentially where the 'page' starts at; this number is something called a unix timestamp, this is measured in milliseconds, so subtracting 60000 from your timestamp will take you back a whole minute. Thankfully there is a much easier way to calculate the timestamp.